Electric furnace for melting metals



y 23, 13. j MAUTSCH 2,159,169

ELECTRIC FURNACE `FOR MELTING METALS Filed Dec. 14, 1937 \N\/E'NTOR RoBaRT MAUTSCH ATTYS.

l Y Mv, M www Patented May 23, 1939 uirE ITES PATENT oFFiE Application December 14, 1937, Serial No. 179,789

In Germany December 24, 1936 2 Claims.

Invelectric arc furnaces for the manufacture of metallurgical products, particularly alloys, by fusion, the means of fusion employed is the heat developed by oney or more electric arcs passing 5. between two or more infusible or at least very refractory electrodes, or between said electrodes and the molten bath itself.l I These electrodes are essentially formed of carbon. They may have a fixed length, necessitating the stoppage of the furnace for their replacement after wear, or they may be fed constantly from the outside to permit continuous working. v

In either system, this intervention of the carbon in the operation of refining the charge of the furnace is not desirable. because it may involve carburisation of the molten bath. Furthermore, the wear of graphite electrodes forms a continual expense which is not negligible, It is an object of the present invention to remedy these disadvantages.

The electric arc furnace according to' the invention comprises metallic electrodes forming the charge of the furnace. 2J This furnace presents the very important advantage that it may be put into operation so to speak-instantaneously, since the striking of the arc causes the ends of the electrodes to melt. It may therefore readily be put into normal service during the few hours when the electricity ompaniesare able to supply current at a reduced ariif.

According to a preferred form of construction, the furnace according to the invention comprises devices for the continuous introduction of the charge in the form `of electrodes consisting essentially of compressed rods of any desired profile and witha basis of metallic fibres which have practically the same cross-section throughout 10 their entire length and are distributed in a practically uniform' manner throughout the entire length of said rods.

A furnace of this kind permits the proportions of the various components of the charge to be readily regulated and 'the composition of the charge to be modied if desired, in order to take into account the result of analyses made on samples of themolten metal or alloy. v

50 The furnace according to the invention mayk in addition be very advantageously provided with a discharge orice for the moltenproducts, so

arranged as to permit the continuous discharge of said products.

5 5 It is thus possible,.by means of a furnace of Yrelatively small dimensions, to produce a high electro-metallurgical furnace according to the 10 invention, l

Figure 2 is a diametrical section on the line II-II of Figure l.

Figure 3 shows a press for effecting a twisting of the whole of the fibres at the same time as 15 a compression.

Figure 4 shows another connection of the source of current according to Figure 1.

' In these various figures, the same reference numerals denotethe same parts. 20

, Figure 1 shows a metallurgical electric arc furnace whereof the electrodes are formed by the agglomeration of metallic fibres under pressure. Said fibres are fine and long elements which have practically the same cross-section throughout their entire length and are considerably interlaced, Said bres are distributed in a practically uniform manner throughout the entire length of the rods which they form.

The electrodes enter the gas-tight enclosure of the furnace I2 through friction bushes I3 of refractory material. Said bushes may likewise be made of some other material cooled by water circulation. Each electrode, in proportion to its e fusion in the furnace under the action of the heat developed by the arc, isformed by a continuous press. y

`These electrodes are formed of metallic fibres 3 which have beenA charged in a hopper 2. They v mass of fibres 3 is drawn from the hopper 2` by 40 rolls which subject vsaid mass to a first compression. The cylinder 5 thus formed is guided in a. tube 6 towards a second continuous press consisting of rolls 1 and 8 (Figures 1 and 2) simil lar to the rolls of rolling mills. 45

f The cylinder 5 is strongly compressed between said-rolls and on leaving the latter forms a-n agglomerated rod Il'which has a very compact texture and is very rigid even when-fabricated' cold and without any binding agent.

Its composition may readily be varied by mixing additional materials with the fibres in the hopper?, either in the form of powder or in the form of fibres. I

Additional materials may likewise be introduced between the two compressions to which the fibres are subjected. In particular, such addition may be eiected by blowing powder between the fibres through nozzles I0.

The rigidity of the electrodes may likewise be increased by imparting a twisting movement to the whole of their fibres during the compression of the latter. For effecting said twisting, it is merely necessary,l instead of directing the axes of the compressing rolls parallel as shown in Figure 2, to cause the axes of these rolls to make a slight angle, as shown in Figure 4 for the rolls 'I' and 8.

The furnace charge may be readily obtained by mixing metallic fibres of diierent metals or alloys or by adding thereto, in the form of powder, either metals or alloys or other substances.

It is likewise possible to introduce into each electrode one or more metallic continuous wires of appropriate nature. It is possible to introduce continuous metallic wires into the mass of which has undergone preliminary compression in a press not shown. Y

The current for feeding the arc I4 is supplied to the electrodes at their entry to the furnace by brushes shown` diagrammatically at I5 in Figure 11. Said brushes may be rendered integral with- Athe bearings of the rolls of the adjacent press, so as to benefit from the good contact resulting from the powerful pressure set up in said presses.

The speed of the rolls 1 and 8 which regulates the feed of the electrodes may be controlled electrically in-accordance with the potential difference between the electrodes by a device such as those employed for maintaining an electric arc of constant and adjustable length.

The furnace itself, lined internally with an appopriate refractory lining, is provided with a gas supply, pipe I6 controlled by a cock l1. At the base of said furnace is a discharge orice I8 for the nshed products I9 and another orifice on a higher level, not shown, for the discharge of the slag 20.

This furnace has the advantage thatitpermits the passage of the arc between electrodes formed by the charge of the furnace itself. It consequently dispenses with the use of expensive carbon electrodes which in many cases exert a detrimental action on the molten bath of metal.

In view of the fact that the operation of refining the charge takes place in the yarc itself between metallic or substantially metallic electrodes, the function of the internal lining of the furnace becomes of secondaryimportance, since the products of the reaction may be immediately discharged to the exterior in a continuous manner. The duration of contact between said products and the lining consequently becomes very short, which considerably simplies the problem of the preservation and maintenance of the linmg.

the form of electrodes into the furnace enables The continuous introduction of the charge in the furnace to be maintained permanently lunder gaseous pressure. whereas the charging of ordinary electric furnaces necessarily interrupts the gas-tightness of their enclosure. The nature of the gas constituting the atmosphere of the furnace may be selected at will, and its pressure may even be raised as high as is desired, either because it is intended to raise the temperature of the arc or because it is desired to facilitate by said pressure the discharge of the molten or pasty products, or again because for special reasons, it is intended to dissolve considerable quantities of gas in the bath of molten metal.

It is also obvious that an electric furnace according to the invention may be constructed in forms different from that shown in Figure 1. More particularly, it is possible to conceive a furnace having a single vertical electrode of the type described, in which the arc passes between said electrode and the molten bath. Of course, it is also possible to employ any number of electrodes.

The composition of the elements which constitute the electrodes of the furnace (fibers and/or additional substances) and the proportion of these elements depend on the nature of the metal or of the alloy to be obtained. The dimensions and the rate of feed of these electrodes may also vary as a function of the dimensions of the furnace and of the composition of the electrodes.

The brushes I5 are connected to the secondary terminals of a transformer 2|, the primary 2Ia of which is connected to alternating current supply mains. Said secondary comprises a plurality of windings, such as 2lb, 2Ic and 2Id connected in series.

Said windings may, however, likewise be connected in parallel as shown in Figure 4. In this but the feed current is higher. 'Ihis parallel connection of the windings 2lb, 2Ic and 2Id of the secondary will be adopted when the furnace is to fore possiblev to pass at will fromarc furnace operation to resistance furnace operation, that is to say to operate the same furnace under very different temperature conditions.

A furnace according to the invention may be utilized for special metallurgical operations, such as the manufacture of special steels, refined ferro alloys. In each case, the composition of the charge should naturally be appropriate to the case, the supply voltage of the furnace is lower object aimed at, in accordance with the knowledge ofthe usual art.

What I claim is:

1. An electric furnace for the manufacture of metallic products, particularly alloys, by fusion, comprising atleast one electrode constituted of compressed metallic elements,frolls similar to the rolls of rolling mills disposed so as to draw `between thema mass of metallic elements* to be compressed and to introduce continuously in the furnacethe compressed electrode which they have formed by lateral compression, `and a discharge orifice for the molten metal arranged in such a enligne c 3 as 'to 't the continuous discharge connectedbetween said Source of current nnd'said of said metal. Y electrodes, said transformer comprising `one pri- 2. An electric for. the manufacture 4of mary winding and a plurality of secondary windg metallic products, particularly alloys, by fusion, ings, and means for connecting said secondary ,5 com metallic electrodes constituting the windings either in series or in parallel. 4ofthe tm'naceasourceof alternating f vto!" said furnace, xox-mer ROBERT MAUTBCH. 

